Arrangement for threading of webs



s. W. WALLIN ARRANGEMENT FOR THREADING OF WEBS Filed Sept. ll, 1964 Aug. 9, 1966 Il f lllwn l I IlxRilIvi. lllmll IIIJLVIIILV INVENTOR: SVEN WERNER WALLIN ATTYs.

United States Patent O ARRANGEMENT FR THREADING F WEBS Sven Werner Wallin, Taby, Sweden, assigner to Aktiebolaget Svenska Flalrtfabriltcn, Stockholm, Sweden Filed Sept. 11, 1964, Ser. No. 395,739

Claims priority, application Sweden, Sept. 13, 1963,

8 Claims. (Cl. 22d- 91) This invention relates to an arrangement adapted for use in the threading, i.e. the guiding and conveying of the leading-end 4of a web intended to be conveyed, through a drier or like treatment plant in one or more zig-Zag runs between reversing rolls mounted in the treatment plant, in such 'a manner that the threading of the leading end is effected by feeding the leading-end through the plant between two ba-nds or belts advanced along each run and preferably at one :side of the plant. Modern dn'ers and similar treatment plants for webs are in many cases constructed as completely closed units. In view of this and of the high speeds now applied, the threading must be carried out automatically.

Threading devices are already previously known. One of .them comprises a completely continuous band adapted for conveying the leading-end mechanically through the plant. However, as the threading in many cases must be carried out while the plant is in operation, and in a condition subjecting the leading-end to complete drying and, as a result thereof, to substantial shrinkage, the aforesaid k-nown `device always includes the risk of the leading-end being torn off `before having .passed through the plant. Moreover, in the case of a break of the long coherent bands, it takes much time to restore the threading device to service. A further disadvantage of these conventional constructions is that they require the pulleys to be journalled in bearings mounted in the hot portion of the drier, thus giving rise to lubrication troubles and to the risk of oil splattering on the material to be dried (paper or the like).

The present invention has as i-ts object to eliminate the aforesaid disadvantages and to ensure reliable threading. The arrangement according to rthe invention is characterized by t-he use of confronting cooperating bands wherein at least one of the aforesaid cooperating bands is divided into a sequence of two or more separate endless bands which at the reversing roll disposed between two such bands are guided over separate turn members provided for each of said bands `and orientated so wit-h respect to their position and distance from the roll, that one of the bands deflects the leading-end about the reversing roll and the next band engages the leading-end after it possibly is exposed temporarily in the free space between the bands.

A suitable embodiment of the invention is characterized in that the turn members are stationary and have a perforated guide surface for the supply of air, and that air distribution boxes are mounted below the band portions between the reversing rolls, the surface of said boxes facing the band being perforated fo-r reducing the friction by the supply of air. The said perforations in the turn members and air distribution boxes may be designed such that the air is caused to flow out in an oblique forward direction and thereby to contribute to the conveyance of the bands. The perforated surface of the air distribution boxes may preferably be shaped like a groove or bowed for assisting in the guidance of the bands. In order to increase t'he contact pressure between the bands or to produce a retaining force between the bands for conveying the leading-end in a vertical direction, the air distribution boxes may be slightly arcuate in longitudinal direction. For preventing the bands from running all the time during the operation of the plant, which would result in their wear, stop members yare provided at each reversing roll,

3,255,267 Patented August 9, 1966 said stop members being adapted upon completion of the threading to be placed between the reversing roll Iand the band in question and thereby to force the band entirely out of contact with the reversing roll. The movement of the stop members and the supply of air are preferably controlled by one and the same control means, thus preventing that one of the said steps is forgotten when the threading is completed.

The invention will be described in greater detail, with reference to the accompanying drawing showing by way of example an embodiment of a threading arrangement according to the invention and wherein:

FIG. l shows a cross-section of a drier equipped with a threading arrangement,

FIG. 2 .shows .a cross-section of an -air distribution box along the line 2-2 in FIG. 1,

FIG. 3 shows -a cross-section of associated stop members, and

FIG. 4 shows another embodiment of a reversing roll with associated stop members.

Referring to the drawings, 1 designates a housing of a drier provided with an opening 2 for introducing a web 3. A corresponding opening for discharging the web is designated by 4. The web is guided through the drier in a plurality of zig-zag runs 5 between reversing rolls 6 mounted in the drier. The threading is effected by feeding the leading-end 3a through the drier between confronting band means advanced along each run and preferably at one side of the drier. The said band means comprise bands 7, 8, 9, 10, 11, a-nd 12. The bands Sand 11 engage one surface of the web 3 in sequence, and the bands 7, 9, 1t? and 12 engage the opposite surface in sequence. Turn members 13, 14 and 15 for the bands, according to the invention, are orientated so with respect to their position and distance from the roll and one -of the bands, for example the band 9, deflects the leading-end at A about the reversing roll 6 and the next band, for example the band 10, engages the leading-end against the confronting band, e.g. the band 8, at B. As a result thereof, in the embodiment s-hown, the leading-end is temporarily freely exposed whereby tension due to shrinkage possibly produced in the leading-end 3a is eliminated. The turn member may comprise elements 13a, 14a, 15a las shown in the drawing to perform the same function. Additional turn members 16 are provided, which, however, do not contribute to producing the aforesaid effect. Air distribution boxes 17 mounted below the band portions are provided with perforations 18 which, in the embodiment shown, are designed in such a manner that they cause the air to flow out in an oblique forward direction, thereby contributing to the conveyance of the band. As appears from FIG. 2, the perforated surface of the air distribution boxes 17 can be bowed or given a groove shape for assisting in the guidance of the bands. The bowed form also assists in conveying the leading end i-n a vertical direction. A modified air distribution box 17a is slightly arcuate in longitudinal direction. For disengaging the bands entirely from the reversing rolls when threading is completed, stop members are mounted at each reversing roll. The said stop members, as appears from FIG. 3, may comprise two concentric pivoted guide members 19 and 20 or, las shown `in FIG. 4, may comprise two guide members 21 and 22 mounted on an axially displaceable bracket 23 having two legs 24 and 25 in movable relationship with one another. The said legs, upon displacement of the bracket 23, are caused to separate and close by a member 26 Iagainst the action of a spring l27. The turn members 15 are pivotable las indicated by the arrows to enable the bands to disengage the reversing rolls and to assert the proper tension `during the threading operation.

After completion of the threading land when the leada reversing roll with ing-end has passed through the whole plant, the separate 3 air supply to the threading arra-ngement must be disconnected and the running of the bands should be stopped, for example by said stop means. In order to prevent forgetting one of these steps, the displacement of the stop means and the air supply are preferably lcontrolled by one and the same control means (not shown).

What I claim is:

1. In a treatment plant for a continuous web having at least one reversing roll mounted to direct the web in at least one zig-zag run through said plant and threading apparatus comprising cooperating confronting band means for engaging opposite surfaces of the leading-end of the web to feed the same through said plant, the improvement wherein one of said band means is carried `about said reversing roll and the other of said band means comprises a sequence of at least two separate bands, said plant including turn members for said separate bands, said turn members engaging said separate bands adjacent said reversing roll and being oriented to cause the first band of said sequence to deect the leading end about the reversing roll and to cause the next band of said sequence to engage the leading-end between said next band and the cooperating confronting band means, and stop members at the reversing roll adapted upon completion of the threading to be displaced between the reversing roll and the one band means, thereby disengaging the one band means entirely from its contact with the reversing roll.

2. A treatment plant according to claim 1 wherein said stop means comprises two guide members spaced from said roll and operable when displaced to engage the band means to effect said disengagement.

3. In a treatment plant for a continuous web having at least one reversing roll mounted to direct the web in at least one zig-zag run through said plant, and threading apparatus comprising cooperating confronting band means for engaging opposite surfaces of the leading-end of the web to feed the same through said plant, one of said band means being carried about said reversing roll and the other of said band means comprising a sequence of at least two separate bands, said plant including turn members for said separate bands, said turn members engaging said separate bands ladjacent said reversing roll and being oriented to cause the first band of said sequence to deiiect the leading-end about the reversing roll and to cause the next band of said sequence to engage the leading-end between said next band land the cooperating confronting band means, the improvement wherein said turn members are stationary having a perforated guide surface for the supply of air, and said plant includes air distribution boxes mounted below the cooperating band means before and beyond the reversing roll, the surfaces of said boxes facing toward the band means being perforated for reducing the friction by the supply of air, and including air supply means for said turn members and said distribution boxes.

4. An arrangement according to claim 3, characterized in that the perforations in the turn members and air distribution boxes are designed such that the air is caused to flow out in an oblique forward direction for contributing to the conveyance of the band means.

5. An arrangement according to claim 3, characterized in that the perforated surface of the air distribution boxes is bowed for assisting in the guidance of the band means.

6. An arrangement according to claim 5, characterized in that the air distribution boxes lare slightly arcuate in the longitudinal direction in order to increase the contact pressure between the band means or to produce a retaining force between the band means for conveying the leading-end in a vertical direction.

7. An arrangement according to claim 3 including stop members at the reversing roll adapted upon completion of the threading to be placed between the reversing roll and the one band means, thereby disengaging the one band means entirely from its contact with the reversing roll.

8. An arrangement according -to claim 7, characterized in that the displacement of said stop members land operation of the air supply means are controlled by one and the same control means.

References Cited by the Examiner UNITED STATES PATENTS 2,141,578 12/1938 Wellmar 226-170 X 2,336,875 12/1943 Macdonald 95-94 2,977,867 4/ 1961 Woodworth 95-75 M. HENSON WOOD, In., Primary Examiner. R. A.' SCHACHER, Assistant Examiner. 

1. IN A TREATMENT PLANT FOR A CONTINUOUS WEB HAVING AT LEAST ONE REVERSING ROLL MOUNTED TO DIRECT THE WEB IN AT LEAST ONE ZIG-ZAG RUN THROUGH SAID PLANT AND THREADING APPARATUS COMPRISING COOPERATING CONFRONTING BAND MEANS FOR ENGAGING OPPOSITE SURFACES OF THE LEADING-END OF THE WEB TO FEED THE SAME THROUGH SAID PLANT, THE IMPROVEMENT WHEREIN ONE OF SAID BAND MEANS IN CARRIED ABOUT SAID REVERSING ROLL AND THE OTHER OF SAID BAND MEANS CONPRISES A SEQUENCE OF AT LEAST TWO SEPARATE BANDS, SAID PLANT INCLUDING TURN MEMBERS FOR SAID SEPARATE BANDS, SAID TURN MEMBERS ENGAGING SAID SEPARATE BANDS ADJACENT SAID REVERSING ROLL AND BEING ORIENTED TO CAUSE THE FIRST BAND OF SAID SEQUENCE TO DEFLECT THE LEADING END ABOUT THE REVERSING ROLL AND TO CAUSE THE NEXT BAND OF SAID SEQUENCE TO ENGAGE THE LEADING-END BETWEEN SAID NEXT BAND AND THE COOPERATING CONFRONTING BAND MEANS, AND STOP MEMBERS AT THE REVERSING ROLL ADAPTED UPON COMPLETION OF THE THREADING TO BE DISPLACED BETWEEN THE REVERSING ROLL AND THE ONE BAND MEANS, THEREBY DISENGAGING THE ONE BAND MEANS ENTIRELY FROM ITS CONTACT WITH THE REVERSING ROLL. 